code: def test_train_args(self):
      parser = argparse.ArgumentParser(description="Testing")
      subparsers = parser.add_subparsers(title="Commands", metavar="")
      Train().add_subparser("train", subparsers)
  
      for serialization_arg in ["-s", "--serialization-dir"]:
          raw_args = [
              "train",
              "path/to/params",
              serialization_arg,
              "serialization_dir",
          ]
  
          args = parser.parse_args(raw_args)
  
          assert args.func == train_model_from_args
          assert args.param_path == "path/to/params"
          assert args.serialization_dir == "serialization_dir"
  
      # config is required
      with self.assertRaises(
          SystemExit
      ) as cm:  # pylint: disable=invalid-name
          args = parser.parse_args(["train", "-s", "serialization_dir"])
          assert (
              cm.exception.code == 2
          )  # argparse code for incorrect usage
  
      # serialization dir is required
      with self.assertRaises(
          SystemExit
      ) as cm:  # pylint: disable=invalid-name
          args = parser.parse_args(["train", "path/to/params"])
          assert cm.exception.code == 2
  
imports: from __future__ import with_statement
  from __future__ import division
  from __future__ import absolute_import
  import argparse
  import os
  import shutil
  import re
  import pytest
  import torch
  from allennlp.common import Params
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.commands.train import Train, train_model, train_model_from_args
  from allennlp.data import DatasetReader, Instance
  from io import open
label_desc: Use image node_id 4 for calling the TestTrain obj's underlying member method code with example usage: obj.test_train_args() without return types